Large-Signal Stability of the Quadratic Boost Converter Using a Disturbance Observer-Based Sliding-Mode Control

Abstract

The quadratic boost (QB) converter is a fourth-order system with a dc gain that is higher than the traditional second-order step-up configuration. The modern controllers that control these high-order dc–dc converters often only guarantee local stability around a steady-state equilibrium point, which is one of their primary drawbacks. In this article, a non-linear robust control law design to attain large-signal stability in this single switch QB converter is presented. In the presence of an unpredictable load, the control objective is to maintain the regulation of an output voltage. The Brunovsky canonical model of the converter was derived first, and the non-linear disturbance observer-based sliding-mode (SM) control law is designed based on it. An observer variable precisely estimates the output disturbances. The detailed process for deriving the control signal is described in this paper and the large-signal stability of the closed-loop converter system is ensured via the Lyapunov function. Finally, some simulation results are shown to validate the usefulness of the given controller.

Normalized Error-Based PI Controller and Its Application to the DC–DC Buck Converter

“…Further Discussions: In this section, the issue of regulation of the load-side voltage of the step-down power converter using the traditional PI control scheme and an improved normalized error-based PI controller is addressed. However, it is important to highlight that the form of the presented control scheme given by ( 19) is not confined to any specific converter and can be suitably used for regulating the load-side voltage of other advanced topologies such as high-order buck converters [17,18] and non-minimum phase boosttype converters [19,20]. The control of non-minimum phase boost converters is especially challenging because their open-loop transfer function (with the output voltage in the numerator and the control signal in the denominator) have zeroes on the right side of the splane.…”